Apparatus for the control of highway crossing signals



March 6, 1945. E. M, ALLEN 2,370,704

APPARATUS FOR THE CONTROL O F HIGHWAY CROSSING SIGNALS Filed Dec. 4, 1942 2 Sheets-Sheet 1 Fig.1

INVENTOR m v EaPlMAllen N- F HIS ATTORNEY E. M. ALLEN 2,370,704

APPARATUS FOR THE CONTROL OF HIGHWAY CRQSSING SIGNALS,

March 6, 1945.

' 2 Sheets-Sheet 2 Y Q 0 E, W 1 M W i m N S Fm wwfiw Q 7 fi mwflw z w PM? w? n D Q. m MY K N I m u m 4 Rfi WW: EA n n cw fimfl U 0 b wmwxwm ww m wwwkg m y T l; 1 m m mm M MR MQN i Y \G T M" m kw vw NM N 5 mi k Patented Mar. 6, 1945 v UNITED STATES PATENT OFFICE i '2,3iti704 APPARATUS FOR THE, CONTROL OF HIGHWAY CROSSING SIGNALS; Earl M. Allen, Swis svale, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application December 4, 1942, Serial No. 467,84lh

7 Claims. 24=6-130) My invention relates to apparatus-for thecontrol of highway crossing signals, and has particular reference to the organization of suchap paratus into novel, and improved systems controlled by railway traflic for operating highway crossing signals.

In highway crossing signal systems of thetype employed for a stretch of trackover which traffic operates in either direction, directional control means are employed to obtain operation of the crossing signal whilea train approaches the crossing and to prevent operation when the train recedes from the crossing. In the ordinary tion is the first occupied and the apparatusthen functions to prevent any train which occupies the other approach section during the timethat the first is still occupied, from causing operation of the signal after the first section becomes vacant. These systems provide proper protection where pnly a single train i involved or where a plurality of trains operating in thesame direction that is, the systems function to cause operation of the signal while any train occupies the firstentered approach section and prevents operation after the first section becomes vacant-either. by

the train in-that section proceedingacross the ,1,

crossing and occupying the other approach section in receding from the crossing, or by thetrain reversing its direction of movement in the first section to recede from the crossing through the first section.

Where, however, trains operating in opposite directions concurrently occupy both approach sections and particularly where track switches are provided in or near the approach sections,

then the usual forms of crossing signal'control systems are subject to improper operation such as either or both preventing signal operation when a train approaches-the crossing and permittingoperation of the signal when a train is receding from a crossing after having passed that crossing. For example, if the first-entered approach section is occupied by a first train and asecond train operating in theopposite-direction enters the other section, then operationl 'of the signal for the second train will be prevented .20 ally established whenever either approach .sec-

or locked out if thefirst train vacates the first section either by being switched away from that section or by reversing its direction and receding from the crossing through the first section. In other words, operation of the signal will be ter-- minated when the first train v'acates the first section, even though the second train is approachtion where trains operatingin opposite directions concurrentlyoccupy- .both approach sections, and

, an object of my present invention is to provide simultaneously occupy the two approach sections, 3

novel and improved highway crossingsignal'control systems of the class described. v 3

Another object of my present invention is to provide novel and improved crossing signalcona trol systems arranged to prevent switchin or other irregular moves from interfering with the operation of a crossing signal. I v

A further object is to provide noveland improved crossing signal systems, incorporating means arranged to lockout operation of the signals only when the train proceeds across the crossing. V

An additional object is to provide novel and improved means in'a signal system for-effecting proper operation of a ignal by at times varying the relative release periods oftwo control'relays.

A further object is to providenovel and improved'means' for attaining proper operation of a crossing signal under various different condi tions of movements of trains in the approach sections. 1 In practicing the invention, the above-mentionedand other important objects and characteristic features of my invention which will becomereadily apparent from the following description are attained by providingv two approach track sections separated from'eachother by a detector track section, and. by controlling two control relays by three track. relays insuch a 5 manner that the relative release interva Offl two control relaysare varied,

out of one of the control rela detector section is'entered, ut. not wn approachsectio I shall describe two forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. l is a diagrammatic view illustrating one form of apparatus embodying my invention. Fig. 2 is a diagrammatic view showing a modified form of the apparatus represented in Fig. l, and also embodying my invention. In each of the two views, similar reference characters have been employed to designate corresponding parts.

Referring to Fig. l, the reference characters and la designate the track rail of a stretch of railway track divided by insulated joints 2 into a plurality of successive adjoining track sections designated by the reference characters T with suitably distinguishing prefixes. Section 2T is intersected at grade by a highway H, and will be termed hereinafter a detector section. Section IT through which an eastbound train, operating from left to right as viewed in the drawings, must travel in approaching the intersection will be termed the eastbound approach section, while the other section 3T through which westbound trains operate in approaching the intersection will be termed the westbound approach section. This latter section alsoincludes a track switch W.

Each of the sections is provided with a track circuit comprising a suitable source of current, such as a battery 3, and a track relay designated by the reference character TR with a prefix corresponding to the prefix of the associated section. Relay ZTR is constantly connected in circuit with the rails of its associated section 2T;

- clud'ng front contacts I and 8, respectively, of

relay 2TR so that when eitherrelay I TR or 3TR is released, it maybe picked up only when its associated section is vacant and relay 2TB is picked up. Relay ITR is provided with a slow releasing repeater relay ITPR energized over a circuit which extends from one terminal B of a suitable source of current, such as a battery not shown, through front contact 9 of relay ITR and the wnding of relay ITPR to the other terminal C of the same source of current. Relay STR is likewise provided with a slow releasing repeater relay 3TPR energized over an obvious circuit including front contact I of relay 3TB.

The reference characters ESR and WSR designate directional control relays, one for either direction of traflic movement on the stretch. The eastbound control relay ESR is normally energized over an obvious circuit including the front point of contact II of relay ITR, and at times may be energized over a stick circuit which extends from terminal B through the back point of contact II of relay ITR, front contact I2 of relay ESR and the winding of relay ESR to terminal 0. Relay ESR is at times provided with a snubbing circuit which includes the windin of the relay, resistor I3 and back contact it of relay 2TB; and with another snubbing circuit including the winding of the relay, its own front contact I5, back contact I6 of relay ITPR and resistor f3.

The other or westbound control relay WSR is normally energized over an obvious circuit including the front point of contact It of "relay 3TB, and at times may be energized over a stick circuit including its own front contact I9 and winding and the back point of contact I3 of relay 3TR. Relay WSR is provided with a first snubbing circuit which connects resistor 28 across its terminals when back contact 2| of relay 2TR is closed; with a second or stick snub circuit which connects resistor across its terminals through a circuit including its own front contact 23 and back contact 22 of relay 3'I'PR; and with a third snub circuit which connects resistor 25 across the relay terminals whenever contact 252 5-21 is closed due to the associated switch W being set for a movement thereover into or out of the turnout.

Located at the intersection is a highway crossing signal of any suitable form, such as, for example, an audible signal in the form of an electric bell XS. The bell i provided with an obvious energizing circuit completed whenever back contact 28 of relay ESR or back contact 29 of relay WSR is closed.

The apparatus of Fig. 1 is in its normal condition, as represented in the drawings, when sections IT, ET and ST are vacant and switch W is set for a main line movement. In this condition of the apparatus; all relays shown in Fig. l are picked up, while signal XS is silent.

For a through train movement, that is, a move ment through all three sections, the apparatus functions to initiate operation of signal XS when a train enters the approach section, maintains that operation when the train occupies the detector section, and prevents or looks out operation of the signal when the tra n clears the detector section and occupies the other approach section on the receding side of the intersection. For example, if an eastbound train enters section IT, relay ITR releases and opens the front point of its contact II to deenergize eastbound control relay ESR. That relay is quick acting and it in turn releases to open its front contact I2 before the back point of contact II of relay ITR .becomes closed. Relay ESR accordingly closes its back contact 28 to complete the energizing circuit for bell XS, thereby setting it into operation When the train enters section 2T, relay 2TB, releases to open the pick-up circuit path of relay I TR at front contact 1, and thereby functions to hold open the track circuit of section IT after the train vacates that section so that relays ITR and ESR remain released to maintain operation of the crossing signal XS until the train vacates section 2T and clears the crossing. Relay 2TR also closes its pack contact 2! to complete a previously mentioned snub circuit path which connects resistor 20 across the terminals of relay WSR with the result that when the train enters section 3T, and relay 3TB releases to open the normal energizing circuit of relay WSR at the front point of contact I8, the flux in the winding of relay WSR is provided with a closed circuit path through which it circulates to snub the release of the relay sufficiently to bridge the transfer time of relay 3TR, or in other words to hold up that relay until the back point of contact l8 of relay 3TR closes to complete the previously traced stick circuit of relay WSR. Relay WSR is therefore maintained energized when the eastbound train occupies section 3T. When the train vacates section 2T and relay 2TR picks up to complete the pick-up circuit path of relay ITR, that relay picks up and in turn picks up relay ESRso that operation of signal XS is ter- WSR is completed.

minated. RelaytTR also opens its back contact 2| to open the snub circuit applied through that contact to the winding of relay 'WSR, but that section IT. A similar :operatmawm take place if a westbound train enters section ST and then relay is now provided with another snub circuit completed through its own front contact 23 and back contact 22 of relay '3' IPR. This latter snub circuit is effective to provide a closed circuit path through which the flux in relay WSR circulates when relay 3TB. picks up after the train vacates section 3T. This circulation of flux snubs or slows up the release of relay WSR sufficiently to bridge the transfer time of relay 3TB and hence maintains relaywsa in its picked-up. position for the interval required for contact l8 of relay 3TB, to pass from its back to its front point wherein the normal energizing circuit of relay From the foregoing description, it is readily apparent that the .apparatus embodying my invention is so arranged that the eastbound directional control relay ESR is released when an eastbound train enters section IT and is retained over a stick circuit including the back point of contact H! of relay 3TB when the eastbound train occupies section 3T. With relay WSR held energized and repeater relay STPR released, relay WSR is snubbed and made slow releasing enough reverses its direction to vacate that section after an eastbound train enters section 1T, or if the westbound train makes a diverging movement over switch W and vacates the section after the eastbound train-enters section IT.

Should a train enter section 3T over switch W,

the operation of the switch will close contact 25-26---"|l'l to applya previously traced snub circuit on relay WSR-and that-relay accordingly will not release when the train enters the section and proceeds to its right-hand end, as viewed in the drawings. It follows, therefore,

that the apparatus embodying my invention makes use of two relays and locks one or the to bridge the transfer time of the contacts of v relay 3TB. from their back to their front points,

thereby to avoid dropping relay WSR momentarily when the train vacates section ST.

The apparatus operates in a correspondingly similar manner for through movements of westbound trains as can be seen from an inspection of the drawings and further detailed description is deemed unnecessary.

The apparatus also is arranged to take care of opposing and other irregular movements near the crossing. For example, if a first train operating in one direction first enters the one approach section for that one direction, and a second train I operating in the opposite directionenters the "other approach section while the first train still occupies the one section, operation of the signal for the second train will be attained after the first train vacates its section either by reversing its direction or by being switched away from the stretch before passing through section 2T. Thus if an eastbound train enters section lT to release relays ITR. and ESR and set signal XS into operation, the apparatus will not be locked up when a westbound train enters section 3T with section IT still occupied by the first train, but instead the westbound train will in turn release relays 3TB. and WSR. so that if the eastbound train reverses its direction and vacates section IT at its lefthand end, as viewed in the drawing, relays ITR. and ESR. will pick up but operation of the signal will be maintained by relay WSR until the westbound train vacates sections 2T and 3T. Also, the westbound train will apply a snub circuit on relay ESR. through back contact l4 of relay 2TB when section 2T is entered, so that relay ESR, will be maintained energized over its stick circuit and operation of signal XS will'be prevented, when the westbound train subsequently occupies other of the relays-out-of 'control of a signal only when the train occupies the detector section, and that the look-out of a relay is made dependent upon the relative release intervals of that relay. These relative release intervals are selectively controlled by the apparatus of the detector section to govern the closure of the back contacts of the relay and prevent'establishing directional control whenever either approach section becomes occupied-and proper operation of the signal is attained for approaching'trains even though opposing and switchingmovements might be involved. a

A modification of the apparatu represented in Fig. l is illustrated in Fig. 2. Referring now to Fig.2, the track relays ITR. and 3TR are constantly connected with th track rails and hence are not controlled in any manner by detector track relay 2TB. Each approach track relay has associatedtherewith a time element relay- TER, two time element stick relays RTESR and N'IESR, and the winding of a control relay of' an interlocking relay XR. Relay XR may for example be of the type shown in Letters Patent of the United States No. 1,799,629 granted April '7, 1931, to W. K. Lockhart and T. J. OMeara and it comprises two control relays EPR and WPR and an interlocking mechanism actuated by the armatures of therel'ays and arrangedso that when either armature is the first to be released, the interlocking mechanism is-actuated to aposition wherein itengages the otherarmature to prevent it from dropping'to a full down position if the other armature is released" when the first is still released. A two-winding polar relay PR of the magnetic stick type also is provided for connecting a snub circuit path across the terminals of relay EPR or WPR, as will be made clear presently.

In the normal condition of the apparatus, sections IT, 2T and 3T are vacant so that relays ITR, ZTR and 3TH are picked up; relay EPR is energized over a circuit which may be traced from terminal B through the front point of contact 30 of relay ITR, front contact 3| of relay ZTR- and the winding of relay EPR to terminal C; and relay WPR also is energized over a circuit which extends from terminal B through the front point of contact 32 of relay BTR, front contact 33 of relay 2TB, and the winding of relay WPR to terminal'C. vSignal XS is provided with an energizing circuit completed at either back contact Moi relay EPR or back contact 35 of relay WPR, and under normal conditions 3 the signal is of course deenergized.

For a train movement through all three sec- 1 tions,,the apparatus operates in accordancewith I the usual custom'to initiate operation oi 'thesi gf j nal when the train entersan approach seams,

maintains 'that operation when the train occupies the detector section, and prevents or locks out operation of the signal when the train clears the detector section and occupies the other approach section in receding from the intersection. For example, if an eastbound train enters section IT, relay ITR. releases to interrupt at the front point of contact 33 the previously traced energizing circuit of relay EPR, whereupon that relay in turn releases to close its back contact 34 and energize signal XS. Relay EPR also completes an alternate circuit for the other relay WPR, which circuit extends from terminal B through back contact 36 of relay EPR, front contact 33 of relay 2TB, and the winding of relay WPR to terminal C. Relay I'I'R also energizes one winding of polar relay PR. and relay INTESR over a circuit extending from terminal B through the back point of contact 30 of relay ITR, back contact 3! of relay EPR, back contact 38 of relay IR'I'ESR, back or checking contact 39 of relay ITER, and then through two alternate paths one comprising back contact 40 of relay IN'I'ESR and the left-hand winding (as viewed in the drawings) of relay PR to terminal C, and the other circuit path comprising back contact 4! of relay l'I'R, from; contact 42 of relay 2TB. and the winding of relay I NTESR to terminal C. The energization' of the left-hand winding of relay PR at this time causes it to operate its polar contact 43 to its left-hand position (as viewed in the drawings) wherein an obvious snub circuit is completed for connecting resistor 44 across the terminals of relay WPR, while relay INTESR picks up to complete a circuit extending from terminal B through front contact 45 of relay lNTESR, back contact 46 of relay IRTESR and the operating element of relay ITER to terminal C. The time element relay ITER accordingly becomes energized and opens its checking or back contact 33. When this happens, the previously traced circuits for relays PR. and INTESR are interrupted but relay PR remains in its left-hand position because of its magnetic stick features while relay INTESR is held energized over a stick circuit which extends from terminal B through the front point of-contact 60 of relay INTESR, back contact 4| of relay ITR, front contact 42 of relay ZTR and the winding of relay INTESR. to terminal C. The time contact 41 of relay ITER is adjusted to close after a time interval substantially longer than that required for a train under ordinary conditions of operation to traverse section IT and enter section 2T. ,If, as has been assumed heretofore, the train makes a through move without pausing in section IT, then section 2T will be entered by the train before relay ITER closes its contact 4?, and when relay 2TB. drops it interrupts the energizing stick circuit of relay lNTESR at front contact 42, whererelay 3TB. retains relay WPR- deenergized and as a result the armatureof the latter relay remains latched up until the train vacates section 3T. When this happens, relay 3TB picks up in turn to pick up relay WPR, and the apparatus is restored to its normal position.

The apparatus will function in a correspondingly similar manner for a through movement of a westbound train, as will be apparent from an inspection of the drawings and further detailed explanation is deemed unnecessary except to point out that when the westbound train enters section 3T and releases relay 3TB, the front point of contact 32 of relay 3TB. opens to release relay WPR whereupon back contact 35 of relay WPR closes to energize signal XS- while back contact 34 of relay WPR. closes to complete a circuit extending from terminal B through back contact 44 of relay WPR, front contact 3| of relay 2TB, and the winding of relay EPR to terminal C. The back point of contact 32 of relay 3TH also closes to energize relays PR and 3N'I'ESR over a circuit extending from terminal B through the back point of contact 32 of relay 3TB, back contact 49 of relay WPR, back contact 50 of relay 3RTESR, back contact SI of relay 3TER, and then through back contact 52 of relay 3NTESR and the right-hand winding of relay PR to terminal C or through hack contact 53 of relay 3TB, front contact 54 of relay 2TB, and the winding of relay SNTESR to terminal C. Relay 3NTESR accordingly picks up and closes its front contact 55 to complete a circuit extending from terminal B through that contact, back contact 56 of relay SRTESR and the winding of relay 3TER, to terminal C; while relay PR. shifts its polar contact 43 to its right-hand position wherein an obvious circuit is completed for connecting resistor 58 across the terminals of relay EPR.

Assuming that the westbound train enters section upon relay INTESR releases to deenergize relay ITER at front contact 45. In addition, front contact 33 of relay 2'I'R interrupt the previously traced energizing circuits for relay WPR and,

that relay accordingly releases its armature which is engaged by the interlocking mechanism and. prevented from closing its back contacts.

When the train enters section 3T, relay 3TB releases but this action has no useful function at this time. When, however, the train vacates section 2T and relay 2TB, picks up, relay EPR becomes energized over its previously traced circuit to terminate operation of signal XS, while 2T before front contact 59 of relay 3TER closes, winding WPR is retained deenergized as long as the train occupies section 3T or 2T, while the armature of relay EPR is released to its latched up position when front contact 3! of relay 2'IR opens when the train occupies section 2T. The armature of relay EPR is maintained latched up by relay ITR being released until the train vacates section I T, whereupon relays I'I'R and EPR pick up and the apparatus is restored to its normal condition.

The snub circuits applied to the windings of relays EPR and WPR function to provide correct operation of signal XS for opposing or switching movements on the stretch. For example, if a train enters an approach section and pauses for a time therein, it is undesirable to continue operation of signalXS for the entire interval and hence the apparatus is arranged to terminate operation of the signal after a predetermined interval, and to restart such operation if the train enters detector section 2T or if another train enters the other approach section. Thus, if an eastbound train enters section IT and pauses therein, relay ITR releases to deenergize relay EPR so that operation of signal XS'is initiated and the previously traced auxiliary energizing circuit of relay WPR is completed through back contact 36 of relay EPR and front contact 33 of relay ZTR. In addition, the left-hand winding of polar relay PR is energized over its preterminate operation of signal XS. Relay ITR also opens its back contact 4| to deenergize relay INTESR, whereupon that relay releases to deenergize relay ITER. Relay ITER is slow in closing its checking or back contact 39, and the apparatus will not restore to its normal condition until that back contact closes so that if the train reenters section IT before back contact 39 of relay ITER, closes, then relay EPR is released to initiate operation ofsignal XS, but relays PR and I NTESR remain deenergized at back contact 39 of relay ITER. After that back contact closes relays PR and INTESR. become energized and relay INTESR in turn energizes relay I'IER. This arrangement insures that the full timing action of relay ITER must elapse for each train enter,- ing the section, and prevents a train from utilizing a portion of the time measured by relay ITER. for a previous train.- In other words, relay ITER must go through its entire pick-up cycle for each train, andto insure this the relay must be restored to its normal condition beforev its pick-up cycle can be commenced;

(2) If the train occupies section IT for the.

full interval required for relay ITER to close its front contact 41, relay IRTESR picks up over a circuit which extends from terminal B through front contact 45 of relay INTESR, front contact 41 of relay ITER and the winding of relay IRTESR to terminal C. Relay lRTESRaccordingly picks up and closes the front point of its contact 46 to complete its own stick circuit which is connected to terminal B at front contact 45 minal C. Relay EPR accordingly picks up to' open its back contact 34 and thus terminate operation of signal XS, to openits back contact 36 and thus open the alternate circuit of relay WPR, and also to release the interlocking mechanism of relay XR to causeit to assume its normal condition. l v

, (3) If, after operation of signal XS has been terminated by the time element apparatus in the foregoing manner, the train vac'ates' section IT at its remote or left-hand end, as viewed in. the drawings, then relay ITR picks up to close'its front contact 30 and complete the normal energizing circuit for relay EPR, and back contact '4! also opens to interrupt the stick circuit for relay in the manner describedfin detail hereinbefore, and the train in section lT'e'nters section 2'1 then relay 2TH is released and relays EPR and WPR are simultaneously deenergized at front contacts'3l and 33 of relay '2'IR,vrespective1y.

Relay WPRis, however, provided with a Smile circuit whichincludes polar contact 43 of relay PR in its left-hand position and which connects resistor 44 across the terminals of the winding of relay WPR. and thus provides a closed circuit path wherein the fiux in the winding of relay WPR circulates to hold up the armature of that relay for an interval of time sufficient to enable the armature of relay EPR. to release to its full down position and actuate the mechanical locking-mechanism into the path of the armature of relay WPR to latch up that armature'when it finally releases; When the train enters section 3T, relay 3TB of course releases to hold the ar mature of relay WPR released .inits latched-up position after the train vacates section and relay 2TR picks up to reenergize the winding of relay EPR. The timing apparatus associated with relay 3TB. is not active at this time becau'se back I contact 49 of relay WPR is open; and back contact also is open so, that operation of signal XS is prevented when the train recedes from the crossing. After the train vacates section 3T, relay 3TB picks up to reenergize relay WPR and the apparatus is restored to its normal condition.

' It is to be noted that when the eastbound train enters section 2T after the timingapparatus has .45 of relay INTESR, and also opens the back point I INTESR whereupon that relay releasesto' release relay IRTESR, and the: apparatus is restored to its normal condition. y

terminated operation of signal XS, relay INTESR becomesdeenergizedat front contact 42 of relay 2TB, and relay INTESR in turn deenergizes relay IRTESR at front contact 45', This operation restores the timingapparatus of section I'T toits normal condition and'thus insures against a 01 lowing eastbound train using the time period measured for the first train.

(4) If, with an eastbound train in section i polar relay PR is in its left-hand position to snub I winding WPR, and the timing apparatus associated with relay ITCR is active, a westbound train enters section 3T, relay 3TB will release but relay WPR will be held up at this time over an auxiliary circuit that includes back contact 36 of relay EPR. (a) Should the train in section IT reverse its direction of travel and vacate the sectionat its left-hand end before relay ITER closes its front contact 41, then relay I'IR will pick up to open its front contact 4| and deenergize relay 'INTESR. Relay INTESR thereupon will release to open its front contact 45 and deenergi'ze relay ITER. Also, the front point of contact 30 of relay ITR will close to complete the normal energizing circuit of relay EPR, and that relay in turn will pick up to open its back contact 36 and thereby open the previously mentioned auxiliary. circuit for the winding of relay Relay WPR accordingly will become deenergized but since it is snubbed at this time it is slow to ture of relay EPR. picks up and the locking mechanism assumes its normal position. When the armature of WPR does release, however, it will drop to its full down position wherein back contact 35 establishes the operating circuit for bell XS, and the mechanical'locking arrangement is actuated into the path of the armature'of relay EPR so that when the westbound train enters section 2T and relay 2TH releases, the resultant release of relay EPR will result in its armature being latched up. When the train enters section IT, relay ITR. will release to hold the armature of relay EPR in its latched position after section 2T is vacated and relay ZTR picks up to energize relay WPR. and thereby terminate operation of the signal. The apparatus is of course restored to its normalcondition when the westbound train vacates section IT and relay ITR picks up to energize relay EPR.

(b) Should the firsttrain in section IT occupy that section (with section 3T also occupied by a second westbound train) for an interval sufficient to enable relay ITER to close its front contact 41, then when relay IR'IESR picks up, relay I'I'ER will become deenergized and after it closes its back contact 39, relay EPR will become energized over its previously traced circuit in cluding the front point of contact 40 of relay INTESR, back contact 39 of relay ITER, the front point of contact 38 of relay IR'I'ESR, front contact 3| of relay ZTR and the winding of relay EPR. When relay EPR, picks up it transfers the control of signal XS to the other relay WPR, in

substantially the same manner as that hereinbefore described in detail in connection with the pick-up of relay ITR when the eastbound train vacates section IT at its lefthand end, and it follows that after the eastbound train vacates section 1T, the signal will be properly controlled for a movement of the westbound train over sections IT, 2T and 3T.

The apparatus will function for the various possible movements of a westbound train either alone or in conjunction with the eastbound train in substantially the same manner as that pointed out in detail hereinbefore for the various movements of an eastbound train. That is to say, the

timing apparatus associated with relay 3TB. is arranged to become active when the section is entered, and it will terminate operation of signal XS if the westbound train occupies the section for an interval of time longer than the pick-up period of relay 3TER. Also, when a westbound train enters section 3T, relay PR is shifted to its right-hand position wherein the winding of relay EPR is snubbed so that operation of signal XS may be transferred to an eastbound train or be retained by the westbound train according as section 2T is entered by an eastbound or a westbound train, respectively.

Fromthe foregoing, it is readily apparent that the apparatus of Fig. 2 embodying my invention is arranged so as to employ two control relays and lock one or the other relay out of control of the signal only when the detector section becomes occupied. In addition, it is to be noted that the look-out of a relay is dependent at times upon the relative release intervals of the relay and that these release intervals are selectively controlled so as to govern the closure of the back contacts and establish the correct directional control of the signal under the various conditions of train movements.

Although I have herein shown and described only a few forms of apparatus for the control of highway crossing signals embodying my invention, it is understood that various changes and modifications ,may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a stretch of railway track intersected by a highway and provided with a highway crossing signal located adjacent to the intersection, two normally energized control relays one for each direction of traflic over said stretch, an energizing circuit for said signal including a back contact of either of said control relays, means controlled by a train on said stretch approaching said intersection for releasing the control relay associated with that trains direction of movement, means controlled by said train when adjacent said highway for increasing the release interval of the other control relay associated with the direction opposite that of the trains direction, and means controlled by said train and effective when the release interval of a control relay is increased for preventing the closure of the back contacts of that relay.

2. In combination with a stretch of railway track intersected by a highway and provided with a highway crossing signal adjacent to the intersection, two control relays one for each-direction of traffic over said stretch and each normally energized in a pick-up circuit, an energizing circuit for said signal including a back contact of either of said control relays, means controlled by a train on said stretch approaching said intersection for interrupting the pick-up circuit of a the control relay associated with that trains direction of movement, means controlled by said approaching train when adjacent said highway for increasing the release interval of the other control relay associated with the direction opposite to that of said trains direction, and means controlled by said train for interrupting the pickup circuit of said other control relay and efiective when the release interval of said other control relay is increased for completing a stick circuit for that relay including its own front contact.

3. In combination with a stretch of railway track divided into two successive adjoining track sections one of which is intersected by a highway,

a highway crossing signal at the intersection, a track circuit including a track relay for each of said track sections, a control relay normally energized in a pick-up circuit including a front contact of the track relay of the other section, means including a back contact of the track relay of said one section for delaying the release of said control relay, a stick circuit for said control relay including its own front contact and a back contact of said other track relay and comtion including a track relay constantly connected in circuit with the rails of said one section, a track circuit for the other of said sections including a track relay connected with the rails of said other section in a stick circuit including-its own -'frontcontact and in a pick-up circuit including i a front contact of said one track relay, a control relay normally energized over a circuit including a front contact of said other track relay, means including a back contact of said one track relay for connecting a resistor across the terminals of said control relay for delaying its release, a stick circuit for said control relay including its own front contact and a back contact of said other track relay and completed only when said control relay is deenergized when its release is delayed by said. release delaying means, and an energizing circuit for said signal completed at a back contact of said control relay.

relay of said intermediate section for increasing the release periods of each of said control relays, and means controlled by each of said approach track relays and effective when the release period of its associated control relay is increased for completing a stick circuit fonthat control relay including its own front contact.

6. In combination with a stretch of railway track divided into two approach track sections separated from each other by an intermediate section intersected by a highway, a track circuit for said intermediate section including a track relay constantly connected with the rails of said intermediate section, a track circuit for each of said approach track sections each including a track relay connected with the track rails of its associated section over a stick circuit path including its own front contact and a pick-up circuit path including a front contact of the track relay of said intermediate section, two control relays one for each approach track relay and each normally energized over a circuit including a front contact of its associated approach track relay, means governed by said intermediate section track relay for at times connecting a resistor across the terminals of each of said control relays for delaying the release of such relays, stick circuit means for each of said control relays comprising its own front contact and a back contact of the associated approach track'relay and completed only'when its associated approach track relay is deenergized when the release of the associated control relay is delayed by said release delaying means, and a highway crossing signal at said intersection energized over a circuit in-' cluding a back contact of either of said control relays.

7. In a, signal system provided for a stretch of railway track over which traffic operates in either direction, two normally energized control relays one for each direction of trafiic over said stretch, a signal, a control circuit for said signal governed by either of said relays, means controlled by a train operating on said stretch for releasing the one of said control relays associated with that trains direction of trafiic, means controlled by said train when adjacent said signal for varying the release interval of the other of said control relays associated with the direction of traffic opposite to that of said trains direction, and-means controlled by said train and efiective when the release interval of said other control relay is varied for rendering said other control relay ineffective to govern the control circuit of said 

